Influence of cycling on microstructure and hydriding/dehydriding properties of nanocrystalline magnesium hydride with nanosized niobium fluoride

Iwona E. Malka ,  Jerzy Bystrzycki 

Military University of Technology, Faculty of Advanced Technology and Chemistry, Kaliskiego 2, Warszawa 00-908, Poland


Magnesium hydride (MgH2) is a promising material for hydrogen storage applications because of its high gravimetric (7.6 wt.%) and volumetric (110 kg m-3) densities and low cost. However, there are some drawbacks limited practical application of this hydride. First of all, it is too stable thermodynamically (H=-75 kJ/mol). It results in high desorption temperature (>400ºC). Moreover, the MgH2 exhibits relatively poor absorption/desorption kinetics below 350ºC. Recently, it has been shown that the sorption kinetics of MgH2 can be dramatically improved by ball milling of MgH2 with some transition metals and their oxides or halides. Among them, NbF5 additive seems most significantly enhance the sorption kinetics of MgH2. However, it is still not clear how the NbF5 promotes the dehydrogenation and hydrogenation reactions. Additionally, there is a lack of information about microstructure and sorption properties of MgH2 with nanosized NbF5 after cycling loading.
In our work we present the effect of cycling on microstructure and hydriding-dehydriding properties of nanocrystalline MgH2 with nanosized NbF5 prepared by mechanical milling. Commercial MgH2 powder was mixed with NbF5 powder (7 wt.%) and subsequently ball milled in an inert atmosphere in a planetary mill. The phase structure, morphology and chemical composition were investigated by XRD, SEM, EDS and DSC-TG. The hydrogen sorption properties and pressure composition isotherms were evaluated using a volumetric Sievert apparatus and temperature programmed desorption. Our results have shown a considerable catalytic effect of NbF5 additive on both the dehydrogenation temperature and hydriding/dehydriding kinetics of MgH2. The obtained nanocomposite exhibits good reversibility in the pressure composition isotherms at 325ºC. However, degradation of nanostructure and hydrogen storage capacity after prolonged cycling are observed, apparently related to the grain growth during cycling at elevated temperature.

Legal notice
  • Legal notice:

    Copyright (c) Pielaszek Research, all rights reserved.
    The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
    In every case, proper references including Author(s) name(s) and URL of this webpage: must be provided.


Related papers
  1. [CEPT] Solvothermal synthesis and characterization of nanomaterials in the Laboratory of Nanostructures for Photonics and Nanomedicine, Center of Bio-Nanomaterials
  2. [CEPT] Studies of solubility of nanoparticles and stability of their suspension
  3. Iinvestigation of nanoparticles by DSC-TG methods accompanied by chemical analysis of emitted gas
  4. Presentation of the  Laboratory of Nanostructures for Photonics and Nanomedicine, Center of Bio-Nanomaterials, CePT
  5. Infrastruktura i specjalizacje nanotechnologii w Polsce na podstawie wyników ankiety NANOFORCE
  6. Badania nanoproszków przy pomocy technik DSC-TG/ QMS-FTIR w Laboratorium Nanostruktur dla Fotoniki i Nanomedycyny CePT
  7. Novel synthesis of ternary magnesium based transition metal hydrides as potential energy storage materials
  8. Hydrogen absorption and desorption kinetics of magnesium hydride nanocomposite with nanosized metal oxides as catalysts
  9. Electron microscopy studies of magnesium hydride
  10. Schock Wave Deformation of Intermetallic Alloys

Presentation: Poster at E-MRS Fall Meeting 2008, Symposium D, by Iwona E. Malka
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-12 09:39
Revised:   2009-06-07 00:48
© 1998-2022 pielaszek research, all rights reserved Powered by the Conference Engine